1. Field of the Invention
Example embodiments relate to an apparatus and method to inspect defects of a semiconductor device in which multiple conditions of electron beams (e-beams) are determined, signals corresponding to secondary electrons generated under the respective conditions are scanned as a plurality of pattern images, and the plurality of pattern images are subtracted to generate a new pattern image.
More specifically, example embodiments relate to an apparatus and method to inspect defects of a semiconductor device in which when a plurality of pattern images are scanned and respectively calculated, secondary electron signals in a top layer may counterbalance each other, while secondary electron signals in an under layer may be amplified, thus generating a new pattern image in which a recess of the under layer becomes almost as clear as a projection of the top layer.
2. Description of the Related Art
In general, fabrication of a semiconductor device involves forming a predetermined material layer on a wafer and patterning the material layer. The patterning process may be followed by a process of inspecting whether a pattern has the same shape and line width as designed or whether there is a defect in the pattern.
A scanning electron microscope (SEM) is typically used to measure the line width of the pattern and detect defects in the pattern. A method of measuring the line width of the pattern using the SEM involves irradiating e-beams onto the pattern formed on the wafer, forming a pattern image by converting a signal corresponding to secondary electrons emitted from the pattern into an image signal, and measuring the line width of the pattern using the pattern image. Also, defects or particles may be detected in the pattern by use of the pattern image obtained using the SEM.